My sister has a D5100 and as I was coaching her on its use over the phone last night we discovered a problem in playback mode. When she is viewing a photo, pushing the left and right arrow moves her through her photos, but the up and down arrows don't let her move through the other info screens for the photo.

I have a D5100 as my backup camera, and I can do this on mine, so I'm baffled. I looked in the manual, and can't see anything that might be accidentally set in the menus that might have blocked that behavior. Does anyone have any idea what might be causing this?